1. Field of the Invention
The invention relates to an apparatus for stabilizing the flight of an arrow. More particularly, this invention pertains to a vane for an arrow that is particularly useful for improving the flight stability and rotation of arrows used either in the field of hunting or in competitive archery.
2. Description of the Prior Art
Historically, feather fletchings or synthetic plastic vanes are individually mounted on the rear end of the arrow shaft to act as guide wings in order to provide stability, rotation and drag to the arrow. The purpose of attaching fletchings or vanes to an arrow is to provide stability, rotation and drag in flight for accuracy in targeting or hunting. Generally, three flat vanes are mounted symmetrically for stability and offset for drag and rotation. For stability each flat vane gives lateral control and when three vanes are used stability is achieved. For drag-rotation the three flat vanes are each offset at a slight angle which gives drag and rotation to the arrow. In recent years two flat vanes were bent at right angles to form a decreasing pocket over the shaft for stability and drag-rotation. More recently, vanes have been formed into a flexible curved decreasing pocket over the arrow shaft to give stability and to moderate drag. Further, these vanes or fletchings cause the arrow to rotate in order to control the bending frequency of the arrow during flight due to column loading. This rotation also prevents hunting arrow broadheads from planing which results in a more accurate flight.
A new problem caused by the materials evolution is the carbon arrow. Carbon arrows are up to 40 percent lighter than aluminum arrows thus making them very critical to drag-gyration. Drag-gyration of the arrow is defined when the rear end of the arrow rotates concentrically about its axis in a circular motion off the flight trajectory line from the center of gravity of the arrow rearward. Also the invention of the compound bow has increased arrow speed causing planing due to speed and rotation problems for hunting arrows with broadheads. A further problem that results from the use of the compound bow is vane fluttering from high frequency fish tailing.
While the prior art has provided some solutions to vane fluttering, controlled drag, and arrow rotation, no solutions have been taught which address drag-gyration, increasing rotation without increasing drag, increasing stability without increasing vane size, and shaft vibration reduction. In an attempt to solve the above problems, Applicant and others have for a number of years been striving to perfect an arrow vane assembly which overcomes the problems associated with "materials evolution" and faster arrow speeds. For example, U.S. Pat. No. 3,815,916 to Meszaros teaches the utilization of thin sections of self-sustaining flexible synthetic resin as vanes which are integrated with a resilient tubular body portion for securing the fletching unit onto the arrow shaft. The vanes are disposed in a helical pattern on the body portion and extend in quarterly directed planes relative to the shaft of the arrow. By so mounting the vanes, they are stressed aerodynamically in flight in opposition to their own rigidity, thereby preventing vane flutter even though the vanes are of extremely thin cross section. By minimizing or eliminating the possibility of vane flutter, the vanes are made thin enough and sufficiently light in weight to compare favorably with feather fletchings in performance characteristics. Further, Meszaros teaches greater durability of the vanes over feather fletching which is less sensitive to weather conditions and is less costly than feather fletching.
It is important to note that in Meszaros the net force generated to rotate the arrow results from the air traveling along the shaft and acting on the quarterly disposed vane which is mounted to the shaft in a somewhat helical relationship to generate rotation of the arrow.
Applicant's own contribution to solve the stated problems associated with prior art arrows includes U.S. Pat. No. 3,853,320 which discloses a vane system which is disposed completely on one side of the arrow shaft and includes vanes extending radially from an axis spaced from the shaft; U.S. Pat. No. 3,756,602 wherein the vanes are disposed on one side of the shaft and slanted or inclined downwardly from the forward end to the rearward end thereof relative to the axis of the shaft; and U.S. Pat. No. 4,003,576 wherein the vane system includes a pair of vanes disposed on one side of the shaft with one of the vanes angled upwardly from the front to rear and the other vane angled downwardly from the front to the rear. All of these prior contributions by Applicant are as a result of an effort to develop a vane system which would not interfere with the arrow rest upon release of the archery arrow.
A further contribution by the Applicant is exemplified by U.S. Pat. No. 4,012,043 which provides a vane system including two vanes disposed on diametrically opposed sides of an arrow shaft with each vane being spaced from the arrow shaft and inclined upwardly and outwardly from the vane shaft in a direction from front to rear extending coextensively with the diameter of the shaft so as not to interfere with the arrow rest upon release of the arrow. The vanes are supported in spaced relationship to the shaft support means defined by oppositely disposed fins extending from diametrically opposed sides of the shaft tangentially to the circumference of the shaft in opposite but parallel directions (note that for each vane the lateral or extended portions from the upstanding planar portions extend over the body of the shaft). Yet a further contribution by the Applicant is U.S. Pat. No. 4,392,654 which teaches an arrow vane consisting of a foot adapted to mount the vane on an arrow shaft along a radial direction and having front and rear ends spaced longitudinally along the shaft, the vane of the fletching projects from the foot and has a continuously curved shape that extends over a major portion of the projecting height of the vane from the foot and is inclined inwardly towards the foot in a rearward direction. The curved shape of the vane extends over the body of the shaft and at its inward inclination in a rearward direction defines a pocket for restriction of air flow while allowing the vane to flex in a manner that moderates drag in response to wind changes. Another embodiment of the vane is made from sheet material such that the vane projects tangentially from an arrow shaft on which the foot is mounted. The sheet material itself has a curved cylindrical shape with the foot extending angularly with respect to the axial direction of the cylindrical shape so as to provide an inward inclination in a rearward direction of the curved vane with the fletching mounted on an associated arrow shaft. The foot is disclosed as having a straight terminal edge and the vane includes a curved terminal edge extending between the front and rear ends of the foot.
As is taught in U.S. Pat. No. 4,392,654 flexing of the vane moderates drag in response to any change in the head or tail wind and, in addition, accommodates for any side wind changes. An increase in head wind produces an increased pressure build-up in the curved vane pocket. Such pressure build-up flexes the vane outwardly to decrease the restriction of air flow and thereby decrease the frictional drag generated during flight such that the arrow does not fall short of its intended target. A decrease in the head wind decreases the pressure build-up in the curved vane pocket. In response to this pressure decrease, the vane flexes inwardly to produce a greater restriction of air flow and thereby increase the frictional drag such that the arrow does not fly over the intended target.
A tail wind produces an increased pressure build-up in the curved vane pocket. Such pressure build-up flexes the vane inwardly to increase the restriction of air flow and thereby increase the frictional drag generated during flight such that the arrow does not over fly its intended target. An increase in the side wind from either direction produces a greater extent of arrow rotation so that the axis of the air flow shaft does not move angularly with respect to the direction of its intended trajectory and change the drag on the arrow as normally takes place with conventional arrows. Each vane flexes outwardly a slight extent as it is blown in the direction of the side wind to provide an increased rotational impetus and each vane flexes inwardly a slight extent during movement into the side wind to facilitate the arrow rotation. This flexing thus increases the speed of the arrow rotation as a result of increased side winds to increase flight stability. Any increase or decrease in side wind results in a corresponding change of degree of vane flexing that takes place in response to such side wind change in order to moderate drag and thereby enhance flight stability along the desired trajectory.
It is clear when viewing the cross-sectional FIGS. 2 through 4 or 5 through 7 that due to the mounting of the fletching along a radial direction of the axis of the shaft, the vane extends over the shaft of the arrow. Such is the case in either direct radial mounting as shown in FIGS. 2 through 4 or tangential mounting such as is shown in FIGS. 5 through 7. By the vane extending over the body of the shaft, as stated in the reference, a pocket is developed under the vane and shaft which allows air to travel therethrough and act on the vane to generate the associated drag and desirable rotation. It is the pocket and its rearward slant that are defined by the teachings of the prior art which generates the drag and effective force causing the rotation of the arrow. However, due to the restricted space between the underside of the vane and the body of the shaft, a limited restriction to air flow is generated within the "pocket" resulting in air disturbances or instabilities which adversely affect stability during flight creating undesirable so called "gyration" or instabilities at long distances with the lighter arrows used in competition and the planing of the heavier broadhead arrows used for hunting purposes.
Further attempts to reduce fluttering are shown in Honda, U.S. Pat. No. 5,039,110, which teaches a substantially cylindrical shaft with front and rear ends and a plurality of fletchings fixed thereto adjacent to its rear end. Each of the fletchings has a generally symmetrical shape that extends from a substantially straight bottom edge. The fletchings are spaced angularly about the shaft and mounted tangentially to its periphery in a stiff design that allows the flight of the arrow to take place substantially unimpeded by flutter accumulation.
Accordingly, what is needed is a vane configuration which allows increased flight stability and increased rotation without increasing drag. This would eliminate broadhead planing, arrow gyration, and reduce dampening of arrow vibration thus allowing increased flight accuracy.